Lithium secondary battery

Abstract

A lithium secondary battery prepared to a negative electrode free battery, and forming lithium metal on a negative electrode current collector through charge. The lithium secondary battery forms lithium metal while being blocked from the atmosphere, and since production of a surface oxide layer (native layer) formed on an existing negative electrode is fundamentally blocked, resulting battery efficiency and lifetime property decline may be prevented.

The invention claimed is: 
     
       1. A lithium secondary battery, comprising
 a positive electrode, a negative electrode, and a separator and an electrolyte interposed therebetween, 
 wherein, in the negative electrode, metal particles are formed on a negative electrode current collector, and 
 lithium metal moved from the positive electrode is formed on the negative electrode current collector in the negative electrode through charge, 
 wherein the metal particles are at least one metal or metalloid selected from the group consisting of silver, gold, magnesium, molybdenum, sodium, osmium, lead, palladium, platinum, plutonium, rubidium, rhodium, ruthenium, selenium, strontium, tantalum, tellurium, uranium, tungsten, and zirconium, 
 wherein the metal particles are included in a content of 0.1% by weight to 40% by weight with respect to the negative electrode current collector. 
 
     
     
       2. The lithium secondary battery of  claim 1 , wherein the lithium metal which is formed on the negative electrode current collector is formed through one-time charge in a voltage range of 4.5 V to 2.5 V. 
     
     
       3. The lithium secondary battery of  claim 1 , wherein the negative electrode further comprises a protective layer formed on a surface in contact with the separator. 
     
     
       4. The lithium secondary battery of  claim 3 , wherein the protective layer comprises any one or more of a lithium ion conducting polymer and an inorganic solid electrolyte. 
     
     
       5. The lithium secondary battery of  claim 4 , wherein the lithium ion conducting polymer is at least one selected from the group consisting of polyethylene oxide (PEO), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP). 
     
     
       6. The lithium secondary battery of  claim 4 , wherein the inorganic solid electrolyte is at least one selected from the group consisting of thio-LISICON (Li 3.25 Ge 0.25 P 0.75 S 4 ), Li 2 S—SiS 2 , LiI—Li 2 S—SiS 2 , LiI—Li 2 S—P 2 S 5 , LiI—Li 2 S—P 2 O 5 , LiI—Li 3 PO 4 —P 2 S 5 , Li 2 S—P 2 S 5 , Li 3 PS 4 , Li 7 P 3 S 11 , Li 2 O—B 2 O 3 , Li 2 O—B 2 O 3 —P 2 O 5 , Li 2 O—V 2 O 5 —SiO 2 , Li 2 O—B 2 O 3 , Li 3 PO 4 , Li 2 O—Li 2 WO 4 —B 2 O 3 , LiPON, LiBON, Li 2 O—SiO 2 , LiI, Li 3 N, Li 5 La 3 Ta 2 O 12 , Li 7 La 3 Zr 2 O 12 , Li 6 BaLa 2 Ta 2 O 12 , Li 3 PO (4−3/2w) Nw (w is w<1) and Li 3.6 Si 0.6 P 0.4 O 4 . 
     
     
       7. The lithium secondary battery of  claim 4 , wherein the protective layer further comprises one or more types of lithium salts selected from the group consisting of LiCl, LiBr, LiI, LiClO 4 , LiBF 4 , LiB 10 Cl 10 , LiPF 6 , LiCF 3 SO 3 , LiCF 3 CO 2 , LiAsF 6 , LiSbF 6 , LiAlCl 4 , CH 3 SO 3 Li, CF 3 SO 3 Li, LiSCN, LiC(CF 3 SO 2 ) 3 , (CF 3 SO 2 ) 2 NLi, (FSO 2 ) 2 NLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, lithium tetraphenylborate and lithium imide. 
     
     
       8. The lithium secondary battery of  claim 4 , wherein the protective layer has a thickness of 10 nm to 50 μm. 
     
     
       9. The lithium secondary battery of  claim 1 , wherein the metal particles are formed on the negative electrode current collector and the metal particles are separated from each other with a gap of greater than or equal to 1 nm and less than 10 μm. 
     
     
       10. The lithium secondary battery of  claim 1 , wherein the positive electrode includes one or more types of positive electrode active materials selected from the group consisting of LiCoO 2 , LiNiO 2 , LiMnO 2 , LiMn 2 O 4 , Li(Ni a Co b Mn c )O 2  (0<a<1, 0<b<1, 0<c<1, a+b+c=1), LiNi 1−Y Co Y O 2 , LiCo 1−Y Mn Y O 2 , LiNi 1−Y Mn Y O 2  (herein, 0≤Y<1), Li(Ni a Co b Mn c )O 4  (0<a<2, 0<b<2, 0<c<2, a+b+c=2), LiMn 2−z Ni z O 4 , LiMn −z Co z O 4  (herein, 0<Z<2), Li x M y Mn 2−y O 4−z A z  (herein, 0.9≤x≤1.2, 0<y<2, 0≤z<0.2, M is one or more of Al, Mg, Ni, Co, Fe, Cr, V, Ti, Cu, B, Ca, Zn, Zr, Nb, Mo, Sr, Sb, W, Ti and Bi, A is one or more anions with valency of −1 or −2), Li 1+a Ni b M′ 1−b O 2−c A′ c  (0≤a≤0.1, 0≤b≤0.8, 0≤c<0.2, M′ is at least one 6-coordinated stable element, and A′ is one or more anions having valency of −1 or −2.), LiCoPO 4  and LiFePO 4 . 
     
     
       11. The lithium secondary battery of  claim 1 , wherein the positive electrode includes a lithium metal compound represented by any one of the following Chemical Formulae 1 to 8:
   Li 2 Ni 1−a M 1   a O 2    [Chemical Formula 1]
 
 in the formula, a is 0≤a<1, and M 1  is one or more types of elements selected from the group consisting of Mn, Fe, Co, Cu, Zn, Mg and Cd;
   Li 2+b Ni 1−c M 2   c O 2+d    [Chemical Formula 2]
 
 
 in the formula, −0.5≤b<0.5, 0≤c≤1, 0≤d<0.3, and M 2  is one or more types of elements selected from the group consisting of P, B, C, Al, Sc, Sr, Ti, V, Zr, Mn, Fe, Co, Cu, Zn, Cr, Mg, Nb, Mo and Cd;
   LiM 3   e Mn 1−e O 2    [Chemical Formula 3]
 
 
 in the formula, e is 0≤e<0.5, and M 3  is one or more types of elements selected from the group consisting of Cr, Al, Ni, Mn and Co;
   Li 2 M 4 O 2    [Chemical 4]
 
 
 in the formula, M 4  is one or more types of elements selected from the group consisting of Cu and Ni;
   Li 3+f Nb 1−g M 5   g S 4−h    [Chemical Formula 5]
 
 
 in the formula, −0.1≤f≤1, 0≤g≤0.5, −0.1≤h≤0.5, and M 5  is one or more types of elements selected from the group consisting of Mn, Fe, Co, Cu, Zn, Mg and Cd;
   LiM 6   i Mn 1−i O 2    [Chemical Formula 6]
 
 
 in the formula, i is 0.05≤i<0.5, and M 6  is one or more types of elements selected from the group consisting of Cr, Al, Ni, Mn and Co;
   LiM 7   2j Mn 2−2j O 4    [Chemical Formula 7]
 
 
 in the formula, j is 0.05≤j<0.5, and M 7  is one or more types of elements selected from the group consisting of Cr, Al, Ni, Mn and Co;
   Li k −M 8   m −N n    [Chemical Formula 8]
 
 
 in the formula, M 8  represents an alkaline-earth metal, k/(k+m+n) is from 0.10 to 0.40, m/(k+m+n) is from 0.20 to 0.50, and n/(k+m+n) is from 0.20 to 0.50.. 
 
     
     
       12. The lithium secondary battery of  claim 1 , wherein the lithium metal formed on the negative electrode current collector is a lithium metal layer having a thickness of 50 nm to 100 μm.